Input selection for an auditory prosthesis

ABSTRACT

Providing stimulation signals for an implanted auditory prosthesis including receiving first and second sound signals at first and second sound input devices, each of the first and second signals having a signal-to-noise ratio; determining a signal parameter related to said signal-to-noise ratio of each of the first and second signals; selecting one of the first and second signals which has the greater signal-to-noise ratio; and generating stimulation signals for the implanted auditory prosthesis based on said selected sound signal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.13/013,615, entitled “Input Selection for an Auditory Prosthesis,” filedon Jan. 25, 2011, now issued as U.S. Pat. No. 9,352,154, which in turnis a Continuation-in-Part of U.S. patent application Ser. No.12/532,633, entitled “Bilateral Input Selection for AuditoryProsthesis,” having a filing/371(c) date of Apr. 26, 2010, nowabandoned, which is a national stage application under 35 USC § 371 (c)of PCT Application No. PCT/AU2008/00415, entitled “Bilateral Input ForAuditory Prostheses,” filed on Mar. 25, 2008, which claims priority fromAustralian Patent Application No. 2007901517, filed on Mar. 22, 2007.The entire disclosure and contents of the above applications are herebyincorporated by reference herein.

BACKGROUND

Field of the Invention

The present invention relates generally to auditory prostheses, and moreparticularly, selecting audio signals for auditory prostheses.

Related Art

Auditory prostheses are provided to assist or replace the perception ofhearing for affected individuals. Such devices include cochlearimplants, middle ear implants, brain stem implants, implanted mechanicalstimulators, electro-acoustic devices, and other devices which provideelectrical stimulation, mechanical stimulation, or both.

In the everyday sound environment, the auditory prosthesis recipientlistens to a target sound, typically speech, in the presence ofbackground noise. In most environments, the locations of the targetsound and noise sources are not the same. For example, source of speechis often in front of the auditory prosthesis recipient as the recipientis usually looking at the person talking. On the other hand, thesource(s) of noise are often on the side or other locations relative tothe recipient when the recipient is facing the speaker.

Background noise interferes with speech understanding, and if the levelof noise approaches that of the target signal, the auditory prosthesisrecipient is unable to effectively distinguish the target sound from thenoise. The signal-to-noise ratio (SNR) is one measure of this influenceof noise upon the target sound signal; a high SNR implies relatively lownoise while a low SNR implies a relatively high noise level.

SUMMARY

In accordance with one aspect of the invention, there is provided amethod for generating stimulation signals in an implanted auditoryprosthesis, comprising: receiving first and second sound signals atfirst and second sound input devices; determining a signal parameter foreach of the first and second signals, wherein the parameter represents anoise floor of each of the first and second sound signals; determining asignal based on the first and second sound signals and the determinedsignal parameters; and generating stimulation signals using saiddetermined signal to cause a hearing percept.

In accordance with another aspect of the invention, there is provided aauditory prosthesis comprising: a first sound input device configured toreceive a first sound signal; a second sound input device configured toreceive a second sound signal; and at least one processor configured todetermine a signal parameter for each of the first and second soundsignals representing a noise floor of each of the first and second soundsignals; determine a signal based on the first and second sound signalsand the determined signal parameters; and generate stimulation signalsbased on the determined signal.

In accordance with yet another aspect of the invention, there isprovided a auditory prosthesis, comprising: a first sound input meansfor receiving a first sound signal; a second sound input means forreceiving a second sound signal; means for determining a parameter foreach of the first and second sound signals, where the parametersrepresents a noise floor of each of the first and second sound signals;means for determining a signal based on the first and second soundsignals and the determined parameters; and means for generatingstimulation signals based on said determined signal.

BRIEF DESCRIPTION OF THE DRAWINGS

Illustrative embodiments of the present invention are described hereinwith reference to the accompanying figures, in which:

FIG. 1 is a perspective view of a cochlear implant in which embodimentsof the present invention may be implemented;

FIG. 2 is an environment in which there is a target speech signal andnoise;

FIG. 3 is a schematic view of a recipient wearing a processor on eachear, in accordance with an embodiment of the present invention;

FIG. 4 is a block diagram of an automatic sensitivity controlarrangement;

FIG. 5 is a block diagram of processors for each side of a recipient, inaccordance with an embodiment of the present invention; and

FIG. 6 is a block diagram showing an alternative implementation ofprocessors for each side of a recipient, in accordance with anembodiment of the present invention; and

FIG. 7 is a block diagram showing an implementation of a bilateralsystem, in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION

Broadly, aspects of the present invention provide an arrangement inwhich sound signals associated with both ears are received. A signalfrom one of the two sides is selected (e.g., the signal having thehighest quality) as the basis for stimulation. The parameter used forselecting which received sound signal to use may be determined, forexample, at one or both of devices fit to each ear of the recipient, orat some other part of the system such as a separate component.

In embodiments, the parameter used for selecting the signal may be anyparameter indicative of the quality of a signal. For example, theparameter may be the signal to noise ratio (SNR) or an estimate of theSNR, where the signal with the highest SNR is used as the basis forstimulation. In another embodiment, the noise in each signal is measuredto obtain a noise floor indicative of the lowest noise level in thesignal over a period of time. This noise floor measurement provides anassessment of the quality of the signal that may then be used forselecting the signal to be used for application of stimulation. Itshould be noted that these are but some examples of parameters forassessing the quality of a signal and in other embodiments otherparameters may be used.

Embodiments of the present invention are described herein primarily inconnection with one type of auditory prosthesis (also sometimes referredto as an “hearing prosthesis”), namely a cochlear prostheses (commonlyreferred to as a cochlear prosthetic devices, cochlear implant, cochleardevices, and the like; simply “cochlear implant” herein.) Cochlearimplants generally refer to auditory prostheses that deliver electricalstimulation to the cochlea of a recipient. As used herein, cochlearimplants also include auditory prostheses that deliver electricalstimulation in combination with other types of stimulation, such asacoustic or mechanical stimulation. It would be appreciated thatembodiments of the present invention may be implemented in any cochlearimplant or other auditory prosthesis now known or later developedincluding auditory brain stimulators (also referred to as brain stemimplants), or implantable auditory prostheses that acoustically ormechanically stimulate components of the recipient's middle or innerear, or any combination of such devices. The devices may have anexternal processor, or may be partially implanted, with only an externalmicrophone, or even completely implanted including the microphone orother sound transducer.

FIG. 1 is perspective view of a conventional cochlear implant, referredto as cochlear implant 100 implanted in a recipient having an outer ear101, a middle ear 105 and an inner ear 107. Components of outer ear 101,middle ear 105 and inner ear 107 are described below, followed by adescription of cochlear implant 100. Although FIG. 1, only illustrates asingle cochlear implant 100, it should be understood that the cochlearimplant system may comprise a cochlear implant 100 fitted to both earsof the recipient. Systems in which a auditory prosthesis (e.g., acochlear implant) are fitted to both of a recipient's ears are referredto as bilateral systems, and systems in which only one auditoryprosthesis is used are referred to as unilateral systems.

In a fully functional ear, outer ear 101 comprises an auricle 110 and anear canal 102. An acoustic pressure or sound wave 103 is collected byauricle 110 and channeled into and through ear canal 102. Disposedacross the distal end of ear cannel 102 is a tympanic membrane 104 whichvibrates in response to sound wave 103. This vibration is coupled tooval window or fenestra ovalis 112 through three bones of middle ear105, collectively referred to as the ossicles 106 and comprising themalleus 108, the incus 109 and the stapes 111. Bones 108, 109 and 111 ofmiddle ear 105 serve to filter and amplify sound wave 103, causing ovalwindow 112 to articulate, or vibrate in response to vibration oftympanic membrane 104. This vibration sets up waves of fluid motion ofthe perilymph within cochlea 140. Such fluid motion, in turn, activatestiny hair cells (not shown) inside of cochlea 140. Activation of thehair cells causes appropriate nerve impulses to be generated andtransferred through the spiral ganglion cells (not shown) and auditorynerve 114 to the brain (also not shown) where they are perceived assound.

Cochlear implant 100 comprises an external component 142 which isdirectly or indirectly attached to the body of the recipient, and aninternal component 144 which is temporarily or permanently implanted inthe recipient. External component 142 typically comprises one or moresound input devices, such as microphone 124 for detecting sound, a soundprocessing unit 126 (also referred to herein as sound processor 126) ora jack for receiving a sound signal from another device, a power source(not shown), and an external transmitter unit 128. In one example, themicrophone 124 is a wireless microphone. External transmitter unit 128comprises an external coil 130 and, preferably, a magnet (not shown)secured directly or indirectly to external coil 130. Sound processingunit 126 processes the output of microphone 124 that is positioned, inthe depicted embodiment, by auricle 110 of the recipient. Soundprocessing unit 126 generates encoded signals, sometimes referred toherein as encoded data signals, which are provided to externaltransmitter unit 128 via a cable (not shown). In an embodiment,microphone 124, sound processing unit 126, and the power source may beincluded in a single housing. This housing may be configured to fitbehind the ear of the device, and is referred to herein as aBehind-the-Ear (BTE) device. It should be understood, however, thatthese components may be housed separately or in a differently configuredhousing.

Internal component 144 comprises an internal receiver unit 132, astimulator unit 120, and an elongate electrode assembly 118. Internalreceiver unit 132 comprises an internal coil 136, and preferably, amagnet (also not shown) fixed relative to the internal coil. Internalreceiver unit 132 and stimulator unit 120 are hermetically sealed withina biocompatible housing, sometimes collectively referred to as astimulator/receiver unit. The internal coil receives power andstimulation data from external coil 130, as noted above. Elongateelectrode assembly 118 has a proximal end connected to stimulator unit120, and a distal end implanted in cochlea 140. Electrode assembly 118extends from stimulator unit 120 to cochlea 140 through mastoid bone119, and is implanted into cochlea 104. In some embodiments electrodeassembly 118 may be implanted at least in basal region 116, andsometimes further. For example, electrode assembly 118 may extendtowards apical end of cochlea 140, referred to as cochlea apex 134. Incertain circumstances, electrode assembly 118 may be inserted intocochlea 140 via a cochleostomy 122. In other circumstances, acochleostomy may be formed through round window 121, oval window 112,the promontory 123 or through an apical turn 147 of cochlea 140.

Electrode assembly 118 comprises a longitudinally aligned and distallyextending array 146 of electrodes 148, sometimes referred to aselectrode array 146 herein, disposed along a length thereof. Althoughelectrode array 146 may be disposed on electrode assembly 118, in mostpractical applications, electrode array 146 is integrated into electrodeassembly 118. As such, electrode array 146 is referred to herein asbeing disposed in electrode assembly 118. Stimulator unit 120 generatesstimulation signals which are applied by electrodes 148 to cochlea 140,thereby stimulating auditory nerve 114.

In cochlear implant 100, external coil 130 transmits electrical signals(i.e., power and stimulation data) to internal coil 136 via a radiofrequency (RF) link. Internal coil 136 is typically a wire antenna coilcomprised of multiple turns of electrically insulated single-strand ormulti-strand platinum or gold wire. The electrical insulation ofinternal coil 136 is provided by a flexible silicone molding (notshown). In use, implantable receiver unit 132 may be positioned in arecess of the temporal bone adjacent auricle 110 of the recipient.

The sound processing unit 126 may store a set of parameters that thesound processing unit 126 uses in processing sound to generate theencoded signals specifying the stimulation signals to be applied byelectrodes 148. This set of parameters and their respective values iscollectively and generally referred to herein as a “parameter map,” a“cochlear map” or “MAP.” A “MAP” is also sometimes referred to as a“program.”

When a recipient first receives a cochlear implant 100, the system 100is fitted or adjusted to the recipient since each recipient experiencesdifferent sound perceptions. It is noted that fitting may also beperiodically performed during the operational use of the cochlearimplant system 100. As used herein the terms “fit,” “adjust,” “program,”“fitting,” “adjusting,” “mapping,” or “programming,” relate todetermining one or more device parameters for a device. These deviceparameters may include parameters resulting in electronic or softwareprogramming changes to the stimulating medical device. The particulardevice parameters determined during the fitting session may varydepending on the multimodal hearing system. In the cochlear implant ofFIG. 1, the device parameters may include one or more of the MAPparameters. These MAP parameters may include, for example, the number ofchannels, T-levels, C-levels, gain, frequency of stimulation,compression characteristic, type of strategy, number of maxima, etc.

FIG. 2 shows a typical sound environment that an auditory prosthesisrecipient may encounter. The user 210 is shown seated on a chair. Thereis a signal that user 210 desires to hear, referred to as target signal222. Typically, target signal 222 is a speech signal. Also illustratedis a source that generates noise signal 224. This noise signal may beany type of noise signal, such as background noise, highway noise, etc.

In the environment of FIG. 2, the user 210 is fitted with either aunilateral or bilateral cochlear implant system. In the unilateralsystem, the cochlear implant system may comprise a BTE device fitted toeither the right or left ear of the user 210, and in a bilateral system,a BTE is fitted to both ears. On average, the probability of noise beingfrom the right or left side of the recipient is equal in the everydaylistening environment. In a unilateral system, when noise is from thesame side as the microphone (e.g., included in the BTE), thesignal-to-noise ratio will be worse than if noise was from the oppositeear side. This phenomenon is known as the headshadow effect, which isessentially the attenuation of noise by the head. Bilaterally implantedusers take advantage of this effect by consciously listening to the earwith the better signal-to-noise ratio, similar to a person with normalhearing. However, as described below, the embodiments of the presentinvention may have advantages for a bilaterally implanted recipient aswell.

To take advantage of this headshadow effect, according to oneimplementation, the auditory prosthesis recipient wears two speechprocessors, with one processor situated at each ear. The two processorsmay be connected by cable for communication, or alternatively by radiofrequency or other wireless communication method not requiring directcable connection.

FIG. 3 illustrates an exemplary auditory prosthesis arrangement, inaccordance with an embodiment of the present invention. As illustrated,an implanted device 314 has been implanted in a user 310. This implanteddevice 314 may be, for example, an internal component of a cochlearimplant such as discussed above with reference to FIG. 1. As shown, aprocessor 312 is provided on the same side as the implanted device 314,which for convenience is referred to herein as the A side. Processor 312may be a sound processor, such as sound processor 126 of FIG. 1 andincluded in a BTE such as discussed above.

A processor 311 is also provided on the contralateral side, which wewill refer to hereafter as the B side. Processor 311 may be identical toor a simplified version of sound processor 126 and may similarly beincluded in a BTE device that also includes one or more microphones. Or,for example, processor 311 may be a relatively simple device, having amicrophone and a transmission arrangement to send raw audio data to theprocessor 312, or at a level of complexity and processing power inbetween. The two processors 311 and 312 are connected by a suitablecommunications link 316, for example a cable or a wirelesscommunications link, such as Bluetooth.

As will be described in more detail below, in this arrangement,processor 312 determines whether the sound signal received on either theA or B side has the best signal-to-noise ratio. The output of thatprocessor is then used as the basis for stimulation. It will beappreciated that the signal-to-noise ratio is only one particularmeasure which is used in the present implementation, and thatembodiments of the present invention can be implemented using manyalternative measured or calculated parameters that are representative orindicative of the quality of the received sound signal.

In another embodiment, there may be a single speech processor and twomicrophones, with one microphone associated with each ear. In such anembodiment, the speech processor would process the signals from each ofthe microphones. It is should be noted that although the presentembodiment is discussed with reference to the presence of a microphoneor other transducer associated with each side of the user's head, inembodiments any suitable arrangement of processors and microphones maybe used. For example, the microphones or other sound transducers may beexternal, partially or totally implanted, totally or partially in theear canal, and associated with processors or not.

In a simple implementation, the B side may be a simple microphone,connected by a cable to a speech processor on the A side. Or, in anembodiment, the processor selecting which sound signal to use forstimulation could be separate from each of the microphone/processordevices fitted to each ear. For example, in a cochlear implant which ispartially or fully implanted, each ear may be fitted with a simplemicrophone device or other device that provides data (e.g., either theraw sound data, the stimulation signals, or something in between) to theimplanted component of the cochlear implant, which determines which ofthe received signals is of better quality (e.g., has a higher SNR).

Embodiments of the present invention may also be applied to abilaterally implanted user. In this case, the selection of which signalto use can be performed by one of the speech processors, or theoperations may be shared among the speech processors.

The required bandwidth and data rate for transmitting the signal betweenthe two processors 311 and 312 over communication link 316 depends onwhat data is being transmitted and the complexity of the device beingused. For example, if the raw audio signal as picked up by the B sidemicrophone is transmitted to the A side, the bandwidth will have to belarge enough to cover the approximately 8 kHz of the typical cochlearimplant audio frequency range at a high enough data rate. The data rateneeds to be high enough to ensure that the signals from each processorare very close to being synchronized when received by the A sideprocessor. If the delay between the signals is too large, then if the Bside has the signal with the higher SNR, when the prosthesis processoron side A comes to process the transmitted signal, the speech perceptsheard by the recipient will not be synchronized with the speaker's lipmovements.

The signal sent from the B side may be subjected to varying levels ofpre-processing. At one extreme is the transmission of raw audio data; atthe other may be a fully formed set of stimulation instruction for theprosthesis. The data transmitted may be at any suitable intermediatelevel.

An audio compression algorithm could be used to reduce the requiredbandwidth. For example, US 2006/0235490 assigned to the presentapplicant, the disclosure of which is hereby incorporated by referenceherein, discloses a suitable coding strategy which could be applied.Other suitable commercial audio compression algorithms could also beused.

Referring back to FIG. 3, in an embodiment, each processor 311 and 312independently measures the signal-to-noise ratio of the sound signalreceived by the processor 311 and 312, respectively, using a suitablealgorithm, for example an automatic sensitivity control (ASC) algorithm.The ASC algorithm automatically adjusts the gain of the initialamplifier in the signal pathway, according to the level of backgroundnoise.

FIG. 4 illustrates a prior art ASC arrangement, for example as describedin relation to a regular, unilateral arrangement in U.S. Pat. No.6,151,400, the disclosure of which is hereby incorporated by reference.In this arrangement, the output of the (initial) amplifier 432 is usedas an input to the ASC 434. The output of the initial amplifier 432 isthe input for the automatic gain control (AGC) amplifier 436. Parametersin the ASC 434 monitor the noise floor, and have pre-set breakpointlevel and timing parameters. This allows the gain to be adjusted inresponse to the ambient noise, and hence in response to the SNR. Theperceptual effect of the ASC 434 is a reduction in the loudness ofbackground noise.

This arrangement of FIG. 4 can be applied to the A and B side signals ofthe system of FIG. 3. For example, FIG. 5 illustrates an exemplary Aside speech processor 512 and a B side processor 511. As shown, speechprocessor 512 comprises an amplifier 542A, an AGC 546A, an ASC 544A, anoise floor comparator 548, and a switch 549. Processor 511 comprises anamplifier 542B, an ASC 544B, and an AGC 546B. In this implementation,for both the A and B side, the respective audio input signal isprocessed by initial amplifier 542A, 542B, respectively, the output ofwhich forms the input to the respective AGC 546A, 546B. Each ASC 444A,444B also receives the amplifier 542A and 542B, respectively, output,and feeds back a control signal to the amplifier 542A and 542B,respectively. Further, according to the present implementation, asnoted, a noise floor comparator 548 is provided on the A side. Each ASC544A, 544B outputs a measure of the noise floor on its respective sideto the noise floor comparator 548. For example, as noted above, the Bside processor 511 may communicate with the A side processor 512 via acommunications link, such as communications link 516 of FIG. 3. In thisimplementation, the characteristics of the ASCs 544A, 544B are the same.

Comparator 548 outputs the difference between the side A and side Bnoise floor values. The value output from the comparator 548 is used tocontrol switch 549. In this implementation, when the comparator 548output value is less than or equal to a threshold value, comparator 548directs switch 549 to deliver the signal from side A to the implant.When the output value from the comparator 548 is above the threshold,comparator 548 directs switch 549 to deliver the signal from side B. Thethreshold value of the comparator 548 can be set as appropriate. Thedefault condition in this implementation may be to present side A.

The noise floor comparator 548 may have an adjustable time constant,typically in the order of seconds. The background noise level from eachASC 544A, 544B may be averaged over a time period, and this averagedvalue is what is provided to the comparator 548 This ensures that thesignal delivered to the user is not constantly changing from side toside, which could be distracting for the user. It is preferred thatrelatively slow time constants are used, so that that the selectionprogram function does not switch quickly across the two processors whichcould be confusing for the auditory prosthesis recipient.

An alternative arrangement is illustrated in FIG. 6. In thisarrangement, instead of each side having an AGC, the processor 611 onthe B side and the processor 612 on the A side share an AGC 656. In thisimplementation, the processor 611 on the B side could be a simplerdevice, such as a headset microphone, including an amplifier 652B andASC function 654B. The speech processor 612 on the A side in thisimplementation performs a noise floor comparison 658, and outputs theselected signal to a shared AGC 656. In all other aspects, theprocessors 611 and 612 may operate in a similar manner to processors 511and 512, respectively, of FIG. 5.

In the above-discussed implementations, the A side processor accordingto the implementations described has the additional function ofreceiving from both processors the measured signal-to-noise ratio. In analternative implementation involving an implanted device, the measuredSNR (or other measure of the quality of the signal) could be providedfrom external processors to the implanted component which then comparesthe signal and determines which signal to used. Or, in yet otherimplementations, this comparison may be performed by some othercomponent.

Although the above discussed embodiments of FIGS. 3, 5 and 6 werediscussed with reference to the cochlear implant system being aunilateral system, as noted above, similar systems could be implementedin a bilateral system. FIG. 7 illustrates an exemplary binaural system,in accordance with an embodiment. As illustrated, the system comprisesan exemplary A side speech processor 712 and a B side speech processor711. As shown, speech processor 712 comprises an amplifier 742A, an AGC746A, an ASC 744A, a noise floor comparator 748, and a selector 749A.Speech processor 711 comprises an amplifier 742B, an ASC 744B, an AGC746B, and a selector 749B. The amplifiers, AGCs, and ASCs for the A andB side processors 712 and 711, respectively, may operate in a similarmanner to the similarly named components of FIG. 5.

In operation, the ASCs 744A and 744B provide a measure of the quality(e.g., signal to noise ratio) of the A and B side input signals,respectively, to the noise comparator 748. Although, in the illustratedembodiment, the noise comparator 748 is included in the A side speechprocessor 712, it should be noted that in other embodiments, thecomparator 748 may be included in the B side processor 711, thefunctionality may be shared between the A and B side processors, or thecomparator may be included in some other device (e.g., in an implantedcomponent).

The output from the noise floor comparator 748 may be provided to theselectors 749A and 749B in the A and B side processors 712 and 711,respectively. If the output from the noise comparator 748 is less thanor equal to a threshold, the A side selector 749A transfers the soundsignal from AGC 746A to the components of the speech processor 712 forgenerating stimulation to be applied to the recipient. If the outputfrom the noise comparator is above the threshold, selector 749Atransfers a null signal so that stimulation is not applied by the A sidespeech processor 712. Or, for example, if the output of the noisecomparator is above the threshold, selector 749A may attenuate (e.g.,reduce the gain of AGC 746A) the sound signal and transfer theattenuated sound signal to the components of speech processor 724 forgenerating stimulation.

Similarly, if the output from the noise comparator 748 is greater thanthe threshold, the B side selector 749B transfers the sound signal fromAGC 746B to the components of the speech processor 711 for generatingstimulation to be applied to the recipient. If the output from the noisecomparator 748 is less than or equal to the threshold, selector 749Btransfers a null signal so that stimulation is not applied by the B sidespeech processor 711. Or, for example, if the output of the noisecomparator is less than or equal to the threshold, selector 749B mayattenuate (e.g., reduce the gain of AGC 746B) the sound signal andtransfer the attenuated sound signal to the components of speechprocessor 711 for generating stimulation. It should be noted that thisis but one example of a mechanism for selecting a sound signal forapplication of stimulation in a bilateral system, and in otherembodiments other mechanisms may be used.

Although the above described embodiments were discussed with referenceto both the A and B sides using standard microphones. In otherembodiments, the microphones may be directional microphones, such as abeamforming microphone (also referred to as a microphone array).

Further, in embodiments, one or more of the microphones may output aplurality of sound signals representative of sound arriving fromdifferent directions. For example, in an embodiment, one or more of themicrophones be a multibeam antenna with one beam pointed towards thefront of the recipient, one pointed perpendicular to the recipient'sear, and one beam pointed towards the rear of the recipient. In such anembodiment, the noise comparator may receive a measure of the quality ofthe signal (e.g., the SNR for the signal) received for each beam, andthen the comparator may select to apply stimulation using the receivedsignal having the highest measured quality (e.g., SNR).

In the above-discussed embodiment of FIGS. 5 and 6, the sound signalsfrom the A and B sides were compared by measuring their respective noisefloors. As noted above, the noise floor is but one example of a measurethat may be used for assessing the quality of the signals on the A and Bside. For example, in other implementations other measures or mechanismsmay be used. For example, in an embodiment, signal to noise ratioestimation techniques may be used to obtain a measure of the quality ofthe signal. Or, for example, in embodiments, the A and B side processorsmay include a component (e.g., software component) for measuring the SNRof the respective input signal. The measured SNR may then be provided toa comparator that compares the received SNR values and outputs a signalspecifying which of the input signals should be used for application ofstimulation. A switch or other selector device(s) may then select andoutput the specified signal. This output signal may then be used toapply stimulation to the recipient.

As noted above, once the appropriate signal is selected, stimulation isapplied by the device to the recipient in accordance with the selectedsignal. The nature of the signal output by the speech processor willvary with the type of device. For a cochlear implant device, the signaloutput from the speech processor may be detailed electrode and amplitudedata. For example, referring back to the embodiments of FIG. 5 thesignal output from the comparator 549 may be used by provided tocomponents (e.g., software, hardware, and or a combination of same) ofthe speech processor 512 that generate detailed electrode and amplitudedata for the application of stimulation. Or, in another embodiment, thespeech processor 512 may provide the data from the AGCs 546A or 546B toan implanted component which determines the electrode and amplitude datafor the generation of stimulation.

For an implanted mechanical stimulation device, the speech processor mayprovide the raw or a modified version of the selected signal to theimplanted component, which then applies mechanical stimulation to therecipient in accordance with the received signal. Or, for example, thespeech processor may use the selected signal to generate instructiondata that is provided to the internal component and specifies how theinternal component is to apply the stimulation.

For an electroacoustic device, the speech processor may use the selectedsignal to generate electrode and amplitude data for the electricalstimulation as well as an audio signal for the acoustic stimulation. Thespeech processor may then provide this electrical stimulation data andaudio signal to the respective devices (e.g., a cochlear implant andloudspeaker, respectively) for applying the electrical and acousticstimulation.

Various implementations of the subject matter described, such as theembodiments of FIGS. 3, 5, 6, and 7 may be realized in digitalelectronic circuitry, integrated circuitry, specially designed ASICs(application specific integrated circuits), computer hardware, firmware,software, and/or combinations thereof. These various implementations mayinclude implementation in one or more computer programs that areexecutable and/or interpretable on a programmable system including atleast one programmable processor, which may be special or generalpurpose, coupled to receive data and instructions from, and to transmitdata and instructions to, a storage system, at least one input device,and at least one output device.

These computer programs (also known as programs, software, softwareapplications, applications, components, or code) include machineinstructions for a programmable processor, and may be implemented in ahigh-level procedural and/or object-oriented programming language,and/or in assembly/machine language. As used herein, the term“machine-readable medium” refers to any computer program product,computer-readable medium, apparatus and/or device (e.g., magnetic discs,optical disks, memory, Programmable Logic Devices (PLDs)) used toprovide machine instructions and/or data to a programmable processor,including a machine-readable medium that receives machine instructionsas a machine-readable signal. Similarly, systems are also describedherein that may include a processor and a memory coupled to theprocessor. The memory may include one or more programs that cause theprocessor to perform one or more of the operations described herein.

Embodiments of the present invention have been described with referenceto several aspects of the present invention. It would be appreciatedthat embodiments described in the context of one aspect may be used inother aspects without departing from the scope of the present invention.

Although the present invention has been fully described in conjunctionwith several embodiments thereof with reference to the accompanyingdrawings, it is to be understood that various changes and modificationsmay be apparent to those skilled in the art. Such changes andmodifications are to be understood as included within the scope of thepresent invention as defined by the appended claims, unless they departthere from.

It will be appreciated by persons skilled in the art that numerousvariations and/or modifications may be made to the invention as shown inthe specific embodiments without departing from the spirit or scope ofthe invention as broadly described. The present embodiments are,therefore, to be considered in all respects as illustrative and notrestrictive. For example, whilst the present invention is described withreference to two microphones, it will be appreciated that the principalcould be applied to a larger number of microphones, or to signals whichare derived from microphone arrays.

What is claimed is:
 1. A method for generating stimulation signals in anauditory prosthesis system comprising: receiving a first one or moresound signals at a first sound input device; receiving a second one ormore sound signals at a second sound input device; determining a firstestimated signal-to-noise ratio (SNR) based on the first one or moresound signals; determining a second estimated SNR based on the secondone or more sound signals; comparing the first SNR to the second SNR toselect a sound signal from one of the first one or more sound signals orthe second one or more sound signals that has the highest SNR; and basedon at least the selected sound signal, generating stimulation signalscapable of causing a hearing percept, wherein at least one of the firstsound input device or the second sound input device comprises abeamforming microphone.
 2. The method of claim 1, wherein each of thefirst SNR and the second SNR are determined over a period of time, andwherein the comparing identifies the sound signal having the highest SNRover the period of time.
 3. The method of claim 1, further comprising:based on the first and second SNRs, determining a first weight for thefirst one or more sound signals and a second weight for the second oneor more sound signals, wherein generating the stimulation signalscomprises: (a) based on the first weight, weighing the first one or moresound signals to provide a first one or more weighted signals; (b) basedon the second weight, weighing the second one or more sound signals toprovide a second one or more weighted signals; (c) providing a combinedsignal by combining the first one or more weighted signals and thesecond one or more weighted signals; and (d) based on the combinedsignal, generating the stimulation signals.
 4. The method of claim 3,further comprising: receiving a third one or more sound signals;determining a third SNR based on the third one or more sound signals;based on the third SNR, determining a third one or more weights for thethird one or more sound signals; and based on the third one or moreweights, weighing the third one or more sound signals to provide a thirdone or more weighted signals, wherein providing the combined signalfurther comprises combining the first one or more weighted signals, thesecond one or more weighted signals, and the third one or more weightedsignals.
 5. The method of claim 1, wherein at least one of the firstsound input device or the second sound input device comprises a wirelessmicrophone.
 6. The method of claim 1, wherein the first sound inputdevice is located at a first ear of a recipient of the auditoryprosthesis and the second sound input device is located at a second earof the recipient of the auditory prosthesis.
 7. The method of claim 1,wherein the auditory prosthesis system comprises a first auditoryprosthesis for a first ear of a recipient and a second auditoryprosthesis for a second ear of the recipient, wherein determining thefirst SNR comprises: determining the first SNR at the first auditoryprosthesis, and wherein determining the second SNR comprises:determining the second SNR at the second auditory prosthesis.
 8. Themethod of claim 7, further comprising: at the first auditory prosthesis,generating, based on the selected signal, data specifying a firststimulation signal; and at the second auditory prosthesis, generating,based on the selected signal, data specifying a second stimulationsignal.
 9. The method of claim 1, wherein the auditory prosthesis systemcomprises a cochlear implant system.
 10. An auditory prosthesis systemcomprising: a first sound input device configured to receive a first oneor more sound signals; a second sound input device configured to receivea second one or more sound signals; and at least one processorconfigured to: determine a first estimated signal-to-noise ratio (SNR)based on the first one or more sound signals; determine a secondestimated SNR based on the second one or more sound signals; compare thefirst SNR to the second SNR to select at least one sound signal from oneof the first one or more sound signals or the second one or more soundsignals; and generate, using the selected at least one sound signal,stimulation signals capable of causing a hearing precept, wherein atleast one of the first sound input device or the second sound inputdevice comprises a beamforming microphone.
 11. The auditory prosthesissystem of claim 10, wherein the at least one processor is configured todetermine each of the first SNR and the second SNR over a period oftime, and wherein to compare the first SNR to the second SNR to selectat least one sound signal from one of the first one or more soundsignals or the second one or more sound signals, the processor isconfigured to identify the sound signal having the highest SNR over theperiod of time.
 12. The auditory prosthesis system of claim 10, whereinthe at least one processor is further configured to: based on the firstSNR, determine a first one or more weights for the first one or moresound signals; based on the second SNR, determine a second one or moreweights for the second one or more sound signals; determine a combinedsignal by: weighing the first one or more sound signals using the firstone or more weights to provide a first one or more weighted signals,weighing the second one or more sound signals using the second one ormore weights to provide a second one or more weighted signals, andcombining at least the first one or more weighted signals and the secondone or more weighted signals; and generate the stimulation signals usingthe combined signal.
 13. The auditory prosthesis system of claim 12,wherein the first sound input device is configured to receive at least athird one or more sound signals, and wherein the at least one processoris further configured to: determine a third SNR based on the third oneor more sound signals; based on the third SNR, determine a third one ormore weights; weight the third one or more sound signals using the thirdweights to provide a third one or more weighted signals; and determinethe combined signal by combining the first one or more weighted signals,the second one or more weighted signals, and the third one or moreweighted signals.
 14. The auditory prosthesis system of claim 10,wherein at least one of the first sound input device or the second soundinput device is a wireless microphone.
 15. The auditory prosthesissystem of claim 10, wherein the auditory prosthesis system comprises afirst auditory prosthesis for a first ear of a recipient and a secondauditory prosthesis for a second ear of the recipient.
 16. The auditoryprosthesis system of claim 15, wherein the at least one processorcomprises: a first processor included in the first auditory prosthesis,wherein the first processor is configured to determine the first SNR andto generate, based on the selected at least one signal, data specifyinga first stimulation signal for the auditory prosthesis system based onthe selected at least one signal; and a second processor included in thesecond auditory prosthesis, wherein the second processor is configuredto determine the second SNR and to generate, based on the selected atleast one signal, data specifying a second stimulation signal for theauditory prosthesis system.
 17. The auditory prosthesis system of claim10, wherein the processor is part of an implanted component that isseparate from the first and second sound input devices.
 18. The auditoryprosthesis system of claim 10, wherein the auditory prosthesis systemcomprises a cochlear implant system.